The Teleajen River in southern Romania is a tributary of the Prahova River. Its source is located in the Ciucaş Mountains in the locality of Cheia, at the junction of headwaters Cheiţa and Tâmpa River. It has a length of 113 km and flows through the Cheia hollow, by the towns of Vălenii de Munte and Boldeşti-Scăeni and the city of Ploieşti.
The following towns and villages are situated along the river Teleajen, from source to mouth: Cheia, Măneciu, Homorâciu, Vălenii de Munte, Gura Vitioarei, Plopeni, Bucov, Dumbrava.
The following rivers are tributaries to the river Teleajen:
Left: Tâmpa, Pridvara, Brădetul, Pârâul lui Iepure, Pleşu, Valea Monteorului, Telejenel, Drajna, Văleanca, Bucovel
Right: Cheiţa, Ciobu, Valea Neagră, Giumelnicu, Mogoşu, Pârâul Stânei, Bobu, Carpenul, Valea Popii, Valea Brusturei, Valea Orăţii, Valea Movilişului, Bouleţu, Valea Mare, Crasna, Bughea, Slănic, Mislea, Dâmbu, Ghighiu, Leaotu
